Bioengineers have developed a strong hydrogel made of proteins that becomes as elastic as skin and blood vessels when exposed to light.

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When exposed to light, the protein-based gel mimics many of the features of elastic tissue such as skin and blood vessels.
Image credit: Nasim Annabi/BWH

While it is still early days – more tests need to be done before it is ready for human trials – they hope the new biomaterial will one day be used in wound healing, such as after injury or surgery.

In the journal Advanced Functional Materials, the team – including members from Brigham and Women’s Hospital (BWH) at Harvard Medical School in Boston, MA – describes the new material, its key properties, and how they tested it in lab tissue and animal models of wound healing.

Co-senior author Nasim Annabi, previously an instructor at BWH, and now a an assistant chemical engineering professor at Northeastern University, Boston, says:

“We are very interested in engineering strong, elastic materials from proteins because so many of the tissues within the human body are elastic.”

One of the challenges bioengineers face in developing such materials is fine-tuning the elasticity and flexibility to match that of body tissue.

“Our hydrogel is very flexible, made from a biocompatible polypeptide and can be activated using light,” notes Prof. Annabi.

Bioengineered hydrogels are manmade jelly-like materials used in medicine to mimic the properties of human tissue. But the ones currently in use have drawbacks, as co-senior author and professor Ali Khademhosseini, who heads a tissue engineering lab at BWH, explains:

“Some synthetic gels degrade into toxic chemicals over time, and some natural gels are not strong enough to withstand the flow of arterial blood through them.”

The researchers say their new biomaterial – called photocrosslinkable elastin-like polypeptide-based (ELP) hydrogel – offers numerous benefits.

The ELP hydrogel is formed when a polypeptide – a chain of amino acids – is exposed to light. Light causes strong bonds to form between the molecules along the chain, making it mechanically stable without having to add chemicals.

When they tested the ELP hydrogel, the researchers found they could control not only its toughness, but how much it swelled, and that it could withstand more stretching than artery tissue.

The authors also note that the hydrogel can be digested by naturally-occurring enzymes, and tests on living cells did not reveal any toxic side-effects.

Turning to how the gel might be used, Prof. Annabi says they can see several possible applications, such as using it a scaffold to grow cells, or incorporating it with cells in a dish and then injecting them to get tissue to regrow. Another possible use is as a sealant to create a protective barrier over a wound.

In further tests, the team found they could improve the wound healing power of the gel by combining it with silica nanoparticles that had already been shown to stop bleeding. Prof. Annabi says such an application would allow doctors to immediately stop bleeding with a single treatment. She concludes:

We see great potential for use in the clinic. Our method is simple, the material is biocompatible, and we hope to see it solve clinical problems in the future.”

Grants from the National Institutes of Health and the National Science Foundation helped to fund the study.

In March 2015, Medical News Today learned about another study that showed how wounds heal faster with help from nanoparticles.

In the Journal of Investigative Dermatology, a team from the Albert Einstein College of Medicine of Yeshiva University describes how a test in mice showed – when compared with no treatment – the experimental nanoparticle therapy helped skin wounds heal twice as fast.